feat: handle template build error

internal/apierror/api_error.go

@@ -0,0 +1,17 @@
+package apierror
+
+import "fmt"
+
+type APIError struct {
+	StatusCode int    `json:"-"`
+	Code       string `json:"code"`
+	Message    string `json:"error"`
+}
+
+func New(status int, code, message string) *APIError {
+	return &APIError{status, code, message}
+}
+
+func (err *APIError) Error() string {
+	return fmt.Sprintf("%s: %s", err.Code, err.Message)
+}